A vinyl chloride-based polymer is a polymer containing at least 50 wt % of a repeating unit derived from a vinyl chloride monomer (VCM), and is used in a variety of applications due to being inexpensive, having an easily controlled hardness, and being applicable to most processing units. Moreover, a vinyl chloride-based polymer is widely used in various fields because it can provide molded products having excellent physical and chemical properties, such as mechanical strength, weather resistance, and chemical resistance. Particularly, a vinyl chloride-based polymer is used for a pipe, a sash and the like for hard use, and is used for wrapping vinyl, a film, a sheet and the like for soft use. In addition, a vinyl chloride-based polymer having a high degree of polymerization may be used, according to the physical properties thereof, for coating high strength and heat-proof wires and for special gaskets.
However, the vinyl chloride-based polymer having a high polymerization degree has lower melt processability than that of a hard or a soft vinyl chloride-based polymer used for general purpose products. Thus, there is a drawback that the productivity of processed molded products is deteriorated.
Thus, when processing temperature is raised to improve the melt processability, there is a problem that discoloration occurs due to the structural characteristic of the vinyl chloride-based polymer. In addition, when a plasticizer is added during processing, the process may be performed at a low temperature. However, since the plasticizer remains in a processed product and greatly affects the physical properties of the processes product, there is a limit to the amount of plasticizer to be used.
Therefore, there is a continuing need for efforts to improve melt processability of a vinyl chloride-based polymer having a high degree of polymerization in the related industry.